1501968-64-4Relevant articles and documents
Practical nonazide synthesis of a D-amino acid oxidase inhibitor via a sequential erlenmeyer-ploechl reaction and ligand-free copper(I) amination protocol
Zhao, Hang,Koenig, Stefan G.,Dankwardt, John W.,Singh, Surendra P.
, p. 198 - 204 (2014)
A synthetic route to fused heterocycle 5 (R1 = Et) was developed that avoids the use of troublesome azido functionality. In this approach, 3-bromofuran aldehyde 7 was synthesized from 3-bromofuran 6 using highly regioselective formylation conditions. The crude solution of 7 was treated with hippuric acid under Erlenmeyer-Ploechl conditions to give enamide product 16, which was isolated by crystallization. Intramolecular amination/cyclization to the fused pyrrole was achieved under ligand-free Cu(I) catalysis in toluene, followed by diamine workup to remove the benzoyl protecting group and residual copper. The final product 5 (R1 = Et) was crystallized directly from the reaction mixture, providing up to 60% overall yield over five chemical steps and two isolations.
